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| | Abstract | | Helicopter-borne magnetic surveys were conducted over Stromboli Volcano and its surrounding areas in 2002 and 2004. Observed data from those surveys were merged and aeromagnetic anomalies for Stromboli Island and its vicinity were reduced onto a smoothed surface. The average magnetization intensity was calculated to be 2.2 A/m for the edifice of Stromboli shallower than 1,200 m below sea level by comparing the observed and synthetic data. Next, apparent magnetization intensity mapping was applied to the observed anomalies using a uniform magnetization of 2.2 A/m as the initial value. A magnetization low occupies the center of the island where the summit craters reside, suggesting demagnetization caused by the heat of conduits and/or hydrothermal activity in addition to the thick accumulation of less magnetic pyroclastic rocks. 3-D magnetic imaging was preliminarily applied to the same magnetic anomalies as well as for the magnetization intensity mapping. A distinctive regional magnetization high is distributed on a saddle area between Stromboli and Basiluzzo islands and extends to the two submarine eruptive centers on the southwestern submarine edifice of Stromboli. A careful examination on the results of the 2-D and 3-D magnetic imaging implies that the saddle area is occupied by volcanic rocks from these eruptive centers and is also underlain by partially and/or completely concealed volcanic structures formed along a NW-SE direction conjugate to the main axis of regional tectonic trend in this area. |
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